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[GMCnet] Fuel tank filler nipple [message #210367] Sat, 08 June 2013 16:51 Go to next message
Jp Benson is currently offline  Jp Benson   United States
Messages: 649
Registered: October 2011
Location: Fla
Karma: 2
Senior Member
It strikes me curious that the filler nipple on the GMC fuel tanks is at the midpoint between the top and bottom of the tank.  Any leaks in the filler tube or connecting hoses would continue until the tank was over half empty.  The only reason I can see for putting the nipple in this location would be that there is no practical position that is higher up on the tank.  Are there any other reasons for this setup?  Has anyone modified their fuel fill system to change this?

I was wondering, why not use oversize body cushions from JimB and raise the body enough to put the filler tube above the frame.  The potential for leaks would be minimized and the filler tube would not be full of gas most of the time.


Thanks,
JP
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Re: [GMCnet] Fuel tank filler nipple [message #210389 is a reply to message #210367] Sat, 08 June 2013 19:09 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma: -62
Senior Member
Jp, the front tank filler spout is located 1/2 way up on the tank to create
an auxiliary fuel supply. When you first fill the system, both tanks fill.
If the main/auxiliary switch on the dash is selected on the main tank, fuel
will be used more or less equally until the supply is 1/2 used. Then you
will continue to use the main/rear tank until the low fuel warning light
comes on. At that time you should have ABOUT 12 GALLONS in the auxiliary
tank. Start hunting for a fuel stop. Your results my vary depending on the
hills in the area that you have just driven through. Gas slashes back and
forth through the common filler tube.
Jim Hupy
Salem, Or
78 Gmc Royale 403
On Jun 8, 2013 2:51 PM, "Jp Benson" <chocomo99@yahoo.com> wrote:

> It strikes me curious that the filler nipple on the GMC fuel tanks is at
> the midpoint between the top and bottom of the tank. Any leaks in the
> filler tube or connecting hoses would continue until the tank was over half
> empty. The only reason I can see for putting the nipple in this location
> would be that there is no practical position that is higher up on the
> tank. Are there any other reasons for this setup? Has anyone modified
> their fuel fill system to change this?
>
> I was wondering, why not use oversize body cushions from JimB and raise
> the body enough to put the filler tube above the frame. The potential for
> leaks would be minimized and the filler tube would not be full of gas most
> of the time.
>
>
> Thanks,
> JP
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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Re: [GMCnet] Fuel tank filler nipple [message #210421 is a reply to message #210389] Sat, 08 June 2013 23:35 Go to previous messageGo to next message
Mr ERFisher is currently offline  Mr ERFisher   United States
Messages: 7117
Registered: August 2005
Karma: 2
Senior Member
like this
http://gmcmotorhome.info/tank.html

and
leaks on the side of the tanks, are not a problem, you can replace these
hose connections without removing the tanks, and JimK has the correct hoses

gene

On Sat, Jun 8, 2013 at 5:09 PM, James Hupy <jamesh1296@gmail.com> wrote:

> Jp, the front tank filler spout is located 1/2 way up on the tank to create
> an auxiliary fuel supply. When you first fill the system, both tanks fill.
> If the main/auxiliary switch on the dash is selected on the main tank, fuel
> will be used more or less equally until the supply is 1/2 used. Then you
> will continue to use the main/rear tank until the low fuel warning light
> comes on. At that time you should have ABOUT 12 GALLONS in the auxiliary
> tank. Start hunting for a fuel stop. Your results my vary depending on the
> hills in the area that you have just driven through. Gas slashes back and
> forth through the common filler tube.
> Jim Hupy
> Salem, Or
> 78 Gmc Royale 403
> On Jun 8, 2013 2:51 PM, "Jp Benson" <chocomo99@yahoo.com> wrote:
>
> > It strikes me curious that the filler nipple on the GMC fuel tanks is at
> > the midpoint between the top and bottom of the tank. Any leaks in the
> > filler tube or connecting hoses would continue until the tank was over
> half
> > empty. The only reason I can see for putting the nipple in this location
> > would be that there is no practical position that is higher up on the
> > tank. Are there any other reasons for this setup? Has anyone modified
> > their fuel fill system to change this?
> >
> > I was wondering, why not use oversize body cushions from JimB and raise
> > the body enough to put the filler tube above the frame. The potential
> for
> > leaks would be minimized and the filler tube would not be full of gas
> most
> > of the time.
> >
> >
> > Thanks,
> > JP
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
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--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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Re: [GMCnet] Fuel tank filler nipple [message #210426 is a reply to message #210367] Sat, 08 June 2013 23:45 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
Senior Member
G'day,

I believe that Manny has modified the fill system as he added an opening door on the driver side.

The body pads from JimB are not high enough to do what you want to do.

There are other "things" that would be affected if you raised the body enough for the fill tubes to clear the frame (crawl under
your GMC and see just how much you'd have to raise it).

Since I have no intention to modify the fuel fill system I'm not inclined to research this further to see exactly what it would
take, sorry.

Regards,
Rob M.

-----Original Message-----
From: Jp Benson

It strikes me curious that the filler nipple on the GMC fuel tanks is at the midpoint between the top and bottom of the tank.  Any
leaks in the filler tube or connecting hoses would continue until the tank was over half empty.  The only reason I can see for
putting the nipple in this location would be that there is no practical position that is higher up on the tank.  Are there any other
reasons for this setup?  Has anyone modified their fuel fill system to change this?

I was wondering, why not use oversize body cushions from JimB and raise the body enough to put the filler tube above the frame.  The
potential for leaks would be minimized and the filler tube would not be full of gas most of the time.

Thanks,
JP

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426
Re: [GMCnet] Fuel tank filler nipple [message #210440 is a reply to message #210367] Sun, 09 June 2013 07:48 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
Jp Benson wrote on Sat, 08 June 2013 17:51

It strikes me curious that the filler nipple on the GMC fuel tanks is at the midpoint between the top and bottom of the tank.  Any leaks in the filler tube or connecting hoses would continue until the tank was over half empty.  The only reason I can see for putting the nipple in this location would be that there is no practical position that is higher up on the tank.  Are there any other reasons for this setup?  Has anyone modified their fuel fill system to change this?

I was wondering, why not use oversize body cushions from JimB and raise the body enough to put the filler tube above the frame.  The potential for leaks would be minimized and the filler tube would not be full of gas most of the time.


Thanks,
JP

JP,

Many GM (and other) vehicles of the period had similar setups. There was not package room to put the fill in the top. Putting in other than a flat-straight location is fraught with problems. The foaming of current "motorfuel" was not an issue.

Except for the difficulty of fuel inventory management, it causes no difficulty and when fuel was 0.45$/gal is was much less of an issue.

The thing I was looking for is a valve to put between the tanks. That would make inventory management infinitely more precise. The ultimate would be valving that allowed one to fill only one (either) of the tanks.

If I find a good answer, I'll tell all about it.

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: [GMCnet] Fuel tank filler nipple [message #210587 is a reply to message #210426] Mon, 10 June 2013 12:57 Go to previous messageGo to next message
Jp Benson is currently offline  Jp Benson   United States
Messages: 649
Registered: October 2011
Location: Fla
Karma: 2
Senior Member
Rob,

Thanks to you, Matt, Gene & Jim H. for the help.   However much help you're willing to provide is appreciated.  Right now I'm just trying to determine feasibility.


I know that Jim B. slices hockey pucks in half somehow so I would only need to convince him to cut them a bit thicker.  He'd probably charge me double but hey I'm helping support a vendor.  I'm doing a frame off restoration so all those other frame to body gotchas can be dealt with as they are installed.  Others have tried this in-situ and had problems with drain tanks and entry steps.  I'll try to find out what Manny did.  It would be nice to relocate the fill neck closer to the tanks.  As long as I don't run to far afoul of DOT, TSA etc etc.


I could get about 1-1/4 inch clearance between the frame cross-members and the body structure.  It would be close but should be enough room for the necessary plumbing. 

There are higher profile isolators available for the front and rear as well.  I won't divulge the part number since I am a dues paying GMCMI member.  Sorry, I just can't resist the banter but don't have time for those other threads.


Well the CG & Cd would be higher and the body should be a bit more wobbly but I don't think by an appreciable amount.

Thanks,
JP




>________________________________
> From: Rob Mueller <robmueller@iinet.net.au>
>To: gmclist@temp.gmcnet.org
>Sent: Sunday, June 9, 2013 12:45 AM
>Subject: Re: [GMCnet] Fuel tank filler nipple
>
>
>G'day,
>
>I believe that Manny has modified the fill system as he added an opening door on the driver side.
>
>The body pads from JimB are not high enough to do what you want to do.
>
>There are other "things" that would be affected if you raised the body enough for the fill tubes to clear the frame (crawl under
>your GMC and see just how much you'd have to raise it).
>
>Since I have no intention to modify the fuel fill system I'm not inclined to research this further to see exactly what it would
>take, sorry.
>
>Regards,
>Rob M.
>
>-----Original Message-----
>From: Jp Benson
>
>It strikes me curious that the filler nipple on the GMC fuel tanks is at the midpoint between the top and bottom of the tank.  Any
>leaks in the filler tube or connecting hoses would continue until the tank was over half empty.  The only reason I can see for
>putting the nipple in this location would be that there is no practical position that is higher up on the tank.  Are there any other
>reasons for this setup?  Has anyone modified their fuel fill system to change this?
>
>I was wondering, why not use oversize body cushions from JimB and raise the body enough to put the filler tube above the frame.  The
>potential for leaks would be minimized and the filler tube would not be full of gas most of the time.
>
>Thanks,
>JP
>
>_______________________________________________
>GMCnet mailing list
>Unsubscribe or Change List Options:
>http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
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Re: [GMCnet] Fuel tank filler nipple [message #210593 is a reply to message #210587] Mon, 10 June 2013 15:17 Go to previous messageGo to next message
GMC_LES is currently offline  GMC_LES   United States
Messages: 569
Registered: October 2009
Location: Montreal
Karma: 0
Senior Member
JP
Since you are doing a frame off restoration you could simply add a piece of 2" or 2.5" square tubing to the top of the frame rails as a riser. This technique has been used on several coaches, most notably some of the Buskirk stretches. Your biggest obstacle will be the steering shaft length and waste tank connections.

Les Burt
Montreal



On 2013-06-10, at 1:57 PM, Jp Benson <chocomo99@yahoo.com> wrote:

> Rob,
>
> Thanks to you, Matt, Gene & Jim H. for the help. However much help you're willing to provide is appreciated. Right now I'm just trying to determine feasibility.
>
>
> I know that Jim B. slices hockey pucks in half somehow so I would only need to convince him to cut them a bit thicker. He'd probably charge me double but hey I'm helping support a vendor. I'm doing a frame off restoration so all those other frame to body gotchas can be dealt with as they are installed. Others have tried this in-situ and had problems with drain tanks and entry steps. I'll try to find out what Manny did. It would be nice to relocate the fill neck closer to the tanks. As long as I don't run to far afoul of DOT, TSA etc etc.
>
>
> I could get about 1-1/4 inch clearance between the frame cross-members and the body structure. It would be close but should be enough room for the necessary plumbing.
>
> There are higher profile isolators available for the front and rear as well. I won't divulge the part number since I am a dues paying GMCMI member. Sorry, I just can't resist the banter but don't have time for those other threads.
>
>
> Well the CG & Cd would be higher and the body should be a bit more wobbly but I don't think by an appreciable amount.
>
> Thanks,
> JP
>
>
>
>
>> ________________________________
>> From: Rob Mueller <robmueller@iinet.net.au>
>> To: gmclist@temp.gmcnet.org
>> Sent: Sunday, June 9, 2013 12:45 AM
>> Subject: Re: [GMCnet] Fuel tank filler nipple
>>
>>
>> G'day,
>>
>> I believe that Manny has modified the fill system as he added an opening door on the driver side.
>>
>> The body pads from JimB are not high enough to do what you want to do.
>>
>> There are other "things" that would be affected if you raised the body enough for the fill tubes to clear the frame (crawl under
>> your GMC and see just how much you'd have to raise it).
>>
>> Since I have no intention to modify the fuel fill system I'm not inclined to research this further to see exactly what it would
>> take, sorry.
>>
>> Regards,
>> Rob M.
>>
>> -----Original Message-----
>> From: Jp Benson
>>
>> It strikes me curious that the filler nipple on the GMC fuel tanks is at the midpoint between the top and bottom of the tank. Any
>> leaks in the filler tube or connecting hoses would continue until the tank was over half empty. The only reason I can see for
>> putting the nipple in this location would be that there is no practical position that is higher up on the tank. Are there any other
>> reasons for this setup? Has anyone modified their fuel fill system to change this?
>>
>> I was wondering, why not use oversize body cushions from JimB and raise the body enough to put the filler tube above the frame. The
>> potential for leaks would be minimized and the filler tube would not be full of gas most of the time.
>>
>> Thanks,
>> JP
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>>
> _______________________________________________
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Les Burt Montreal 1975 Eleganza 26ft A work in Progress
Re: [GMCnet] Fuel tank filler nipple [message #210596 is a reply to message #210587] Mon, 10 June 2013 15:52 Go to previous messageGo to next message
powerjon is currently offline  powerjon   United States
Messages: 2446
Registered: January 2004
Karma: 5
Senior Member
Jp,
If you're doing a frame off restoration, why not raise the body 2inchesup higher off the frame. The Buskirk Stretch coaches that were built were done that way. I run MPFI and have the clearance as to not the raised the engine hatch. Use 1 1/2 inch unistrut on the chassis cross members as a spacer and then the 1/2 inch body pad. Provides all sort of clearance for fuel and air lines under the coach. If you're going to go thru the pain to raise it why not go all the way to 2 inches. The ride height would still be set of the frame and not the body.

JR Wright
78 Buskirk Stretch
Michigan

On Jun 10, 2013, at 1:57 PM, Jp Benson <chocomo99@yahoo.com> wrote:

> Rob,
>
> Thanks to you, Matt, Gene & Jim H. for the help. However much help you're willing to provide is appreciated. Right now I'm just trying to determine feasibility.
>
>
> I know that Jim B. slices hockey pucks in half somehow so I would only need to convince him to cut them a bit thicker. He'd probably charge me double but hey I'm helping support a vendor. I'm doing a frame off restoration so all those other frame to body gotchas can be dealt with as they are installed. Others have tried this in-situ and had problems with drain tanks and entry steps. I'll try to find out what Manny did. It would be nice to relocate the fill neck closer to the tanks. As long as I don't run to far afoul of DOT, TSA etc etc.
>
>
> I could get about 1-1/4 inch clearance between the frame cross-members and the body structure. It would be close but should be enough room for the necessary plumbing.
>
> There are higher profile isolators available for the front and rear as well. I won't divulge the part number since I am a dues paying GMCMI member. Sorry, I just can't resist the banter but don't have time for those other threads.
>
>
> Well the CG & Cd would be higher and the body should be a bit more wobbly but I don't think by an appreciable amount.
>
> Thanks,
> JP
>
>
>
>
>> ________________________________
>> From: Rob Mueller <robmueller@iinet.net.au>
>> To: gmclist@temp.gmcnet.org
>> Sent: Sunday, June 9, 2013 12:45 AM
>> Subject: Re: [GMCnet] Fuel tank filler nipple
>>
>>
>> G'day,
>>
>> I believe that Manny has modified the fill system as he added an opening door on the driver side.
>>
>> The body pads from JimB are not high enough to do what you want to do.
>>
>> There are other "things" that would be affected if you raised the body enough for the fill tubes to clear the frame (crawl under
>> your GMC and see just how much you'd have to raise it).
>>
>> Since I have no intention to modify the fuel fill system I'm not inclined to research this further to see exactly what it would
>> take, sorry.
>>
>> Regards,
>> Rob M.
>>
>> -----Original Message-----
>> From: Jp Benson
>>
>> It strikes me curious that the filler nipple on the GMC fuel tanks is at the midpoint between the top and bottom of the tank. Any
>> leaks in the filler tube or connecting hoses would continue until the tank was over half empty. The only reason I can see for
>> putting the nipple in this location would be that there is no practical position that is higher up on the tank. Are there any other
>> reasons for this setup? Has anyone modified their fuel fill system to change this?
>>
>> I was wondering, why not use oversize body cushions from JimB and raise the body enough to put the filler tube above the frame. The
>> potential for leaks would be minimized and the filler tube would not be full of gas most of the time.
>>
>> Thanks,
>> JP
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
Re: [GMCnet] Fuel tank filler nipple [message #210688 is a reply to message #210587] Tue, 11 June 2013 11:26 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
Senior Member
Jp,

I just went out and crawled under Double Trouble and took the following measurements:

a) Bottom of frame rail to bottom of fuel filler hose: 2 1/2"

b) Diameter of fuel filler hose: 1 1/2"

c) Height of frame: 6"

It was kinda hard to make these measurements so I'd say they are not 100% correct but good enough for the following.

Since the frame is 6" tall and the bottom of fuel filler hose is 2 1/2" from the bottom of the frame I reckon you would have to
raise the body 3 1/2" for the bottom of the fuel filler hose to clear the top of the frame.

I may have this all wrong! ;-)

Regards,
Rob M.

-----Original Message-----
From: Jp Benson

Rob,

Thanks to you, Matt, Gene & Jim H. for the help.   However much help you're willing to provide is appreciated.  Right now I'm just
trying to determine feasibility.

I know that Jim B. slices hockey pucks in half somehow so I would only need to convince him to cut them a bit thicker.  He'd
probably charge me double but hey I'm helping support a vendor.  I'm doing a frame off restoration so all those other frame to body
gotchas can be dealt with as they are installed.  Others have tried this in-situ and had problems with drain tanks and entry steps. 
I'll try to find out what Manny did.  It would be nice to relocate the fill neck closer to the tanks.  As long as I don't run to far
afoul of DOT, TSA etc etc.

I could get about 1-1/4 inch clearance between the frame cross-members and the body structure.  It would be close but should be
enough room for the necessary plumbing. 

There are higher profile isolators available for the front and rear as well.  I won't divulge the part number since I am a dues
paying GMCMI member.  Sorry, I just can't resist the banter but don't have time for those other threads.

Well the CG & Cd would be higher and the body should be a bit more wobbly but I don't think by an appreciable amount.

Thanks,
JP




>________________________________
> From: Rob Mueller <robmueller@iinet.net.au>
>To: gmclist@temp.gmcnet.org
>Sent: Sunday, June 9, 2013 12:45 AM
>Subject: Re: [GMCnet] Fuel tank filler nipple
>
>
>G'day,
>
>I believe that Manny has modified the fill system as he added an opening door on the driver side.
>
>The body pads from JimB are not high enough to do what you want to do.
>
>There are other "things" that would be affected if you raised the body enough for the fill tubes to clear the frame (crawl under
>your GMC and see just how much you'd have to raise it).
>
>Since I have no intention to modify the fuel fill system I'm not inclined to research this further to see exactly what it would
>take, sorry.
>
>Regards,
>Rob M.
>
>-----Original Message-----
>From: Jp Benson
>
>It strikes me curious that the filler nipple on the GMC fuel tanks is at the midpoint between the top and bottom of the tank.  Any
>leaks in the filler tube or connecting hoses would continue until the tank was over half empty.  The only reason I can see for
>putting the nipple in this location would be that there is no practical position that is higher up on the tank.  Are there any
other
>reasons for this setup?  Has anyone modified their fuel fill system to change this?
>
>I was wondering, why not use oversize body cushions from JimB and raise the body enough to put the filler tube above the frame. 
The
>potential for leaks would be minimized and the filler tube would not be full of gas most of the time.
>
>Thanks,
>JP
>
>_______________________________________________
>GMCnet mailing list
>Unsubscribe or Change List Options:
>http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426
Re: [GMCnet] Fuel tank filler nipple [message #210694 is a reply to message #210688] Tue, 11 June 2013 12:36 Go to previous messageGo to next message
Jp Benson is currently offline  Jp Benson   United States
Messages: 649
Registered: October 2011
Location: Fla
Karma: 2
Senior Member
You're right, there's no getting around the location of the filler nipple.  The filler tube however can be moved above the frame if there is enough clearance between the top of the crossmember and the bottom of the body.  Top of the crossmember is ~1/2" below top of frame.  Add the thickness of the standard body cushion and get a total of 1".   A little more space and there's room to work with.  Now the original filler tube may be obsolete and the whole fill system (down to the nipple) is open to redesign.  Which may or may not be a good idea.  In another thread, Dave mentions using 1" copper tubing.  The factory design with the fill neck by the driver window and 10' long fill tube leveled halfway up the tanks doesn't seem very "ergonomic" to me.  Maybe there are reasons that I don't comprehend but so far nothing too serious has come up.

JP







>________________________________
> From: Rob Mueller <robmueller@iinet.net.au>
>To: gmclist@temp.gmcnet.org
>Sent: Tuesday, June 11, 2013 12:26 PM
>Subject: Re: [GMCnet] Fuel tank filler nipple
>
>
>Jp,
>
>I just went out and crawled under Double Trouble and took the following measurements:
>
>a) Bottom of frame rail to bottom of fuel filler hose: 2 1/2"
>
>b) Diameter of fuel filler hose: 1 1/2"
>
>c) Height of frame: 6"
>
>It was kinda hard to make these measurements so I'd say they are not 100% correct but good enough for the following.
>
>Since the frame is 6" tall and the bottom of fuel filler hose is 2 1/2" from the bottom of the frame I reckon you would have to
>raise the body 3 1/2" for the bottom of the fuel filler hose to clear the top of the frame.
>
>I may have this all wrong! ;-)
>
>Regards,
>Rob M.
>
>-----Original Message-----
>From: Jp Benson
>
>Rob,
>
>Thanks to you, Matt, Gene & Jim H. for the help.   However much help you're willing to provide is appreciated.  Right now I'm just
>trying to determine feasibility.
>
>I know that Jim B. slices hockey pucks in half somehow so I would only need to convince him to cut them a bit thicker.  He'd
>probably charge me double but hey I'm helping support a vendor.  I'm doing a frame off restoration so all those other frame to body
>gotchas can be dealt with as they are installed.  Others have tried this in-situ and had problems with drain tanks and entry steps. 
>I'll try to find out what Manny did.  It would be nice to relocate the fill neck closer to the tanks.  As long as I don't run to far
>afoul of DOT, TSA etc etc.
>
>I could get about 1-1/4 inch clearance between the frame cross-members and the body structure.  It would be close but should be
>enough room for the necessary plumbing. 
>
>There are higher profile isolators available for the front and rear as well.  I won't divulge the part number since I am a dues
>paying GMCMI member.  Sorry, I just can't resist the banter but don't have time for those other threads.
>
>Well the CG & Cd would be higher and the body should be a bit more wobbly but I don't think by an appreciable amount.
>
>Thanks,
>JP
>
>
>
>
>>________________________________
>> From: Rob Mueller <robmueller@iinet.net.au>
>>To: gmclist@temp.gmcnet.org
>>Sent: Sunday, June 9, 2013 12:45 AM
>>Subject: Re: [GMCnet] Fuel tank filler nipple
>>
>>
>>G'day,
>>
>>I believe that Manny has modified the fill system as he added an opening door on the driver side.
>>
>>The body pads from JimB are not high enough to do what you want to do.
>>
>>There are other "things" that would be affected if you raised the body enough for the fill tubes to clear the frame (crawl under
>>your GMC and see just how much you'd have to raise it).
>>
>>Since I have no intention to modify the fuel fill system I'm not inclined to research this further to see exactly what it would
>>take, sorry.
>>
>>Regards,
>>Rob M.
>>
>>-----Original Message-----
>>From: Jp Benson
>>
>>It strikes me curious that the filler nipple on the GMC fuel tanks is at the midpoint between the top and bottom of the tank.  Any
>>leaks in the filler tube or connecting hoses would continue until the tank was over half empty.  The only reason I can see for
>>putting the nipple in this location would be that there is no practical position that is higher up on the tank.  Are there any
>other
>>reasons for this setup?  Has anyone modified their fuel fill system to change this?
>>
>>I was wondering, why not use oversize body cushions from JimB and raise the body enough to put the filler tube above the frame. 
>The
>>potential for leaks would be minimized and the filler tube would not be full of gas most of the time.
>>
>>Thanks,
>>JP
>>
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Re: [GMCnet] Fuel tank filler nipple [message #210767 is a reply to message #210694] Wed, 12 June 2013 05:13 Go to previous messageGo to next message
mike miller   United States
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
Senior Member
Jp Benson wrote on Tue, 11 June 2013 10:36

...  Now the original filler tube may be obsolete and the whole fill system (down to the nipple) is open to redesign.  Which may or may not be a good idea.  In another thread, Dave mentions using 1" copper tubing.  The factory design with the fill neck by the driver window and 10' long fill tube leveled halfway up the tanks doesn't seem very "ergonomic" to me.  Maybe there are reasons that I don't comprehend but so far nothing too serious has come up.


If I understand it correctly, the design and location of the fill "system" was to keep it from protruding into the living space. If it is your coach and you are designing the interior, you could design around any protrusions. Twisted Evil Also, it was still in the days of full service gas stations when these where designed. You could sit in your seat and watch the station attendant fill the tank.

A few have moved the fill(s) to other locations, including to the other side of the coach. There isn't any reason that the tanks HAVE to be connected.

Another thought, a spacer on top the frame (effectively a body lift) would allow for a larger (thicker) "custom" fuel tank, maybe even large enough that you only would need one tank. That would simplify the fill, vent and "use" plumbing.



Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo' http://m000035.blogspot.com
Re: [GMCnet] Fuel tank filler nipple [message #210777 is a reply to message #210767] Wed, 12 June 2013 07:57 Go to previous messageGo to next message
Jp Benson is currently offline  Jp Benson   United States
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Registered: October 2011
Location: Fla
Karma: 2
Senior Member
Mike,

Thanks for those observations.  Relocation of the filler neck would require invading the living space.  This would also require the filler neck to go over the outside frame rail and more clearance would be needed.  Since the frame rail is nearly a foot inside the body it gets even more problematic.  One positive with the factory fill neck location is protection from side impact.  With those facts in mind I will limit my consideration to raising the body enough to move the fill tube above the frame cross-members.


Thanks, JP




>________________________________
> From: Mike Miller <m000035@gmail.com>
>To: gmclist@temp.gmcnet.org
>Sent: Wednesday, June 12, 2013 6:13 AM
>Subject: Re: [GMCnet] Fuel tank filler nipple
>
>
>
>
>Jp Benson wrote on Tue, 11 June 2013 10:36
>> ...  Now the original filler tube may be obsolete and the whole fill system (down to the nipple) is open to redesign.  Which may or may not be a good idea.  In another thread, Dave mentions using 1" copper tubing.  The factory design with the fill neck by the driver window and 10' long fill tube leveled halfway up the tanks doesn't seem very "ergonomic" to me.  Maybe there are reasons that I don't comprehend but so far nothing too serious has come up.
>
>
>If I understand it correctly, the design and location of the fill "system" was to keep it from protruding into the living space.  If it is your coach and you are designing the interior, you could design around any protrusions.  :twisted:  Also, it was still in the days of full service gas stations when these where designed.  You could sit in your seat and watch the station attendant fill the tank.
>
>A few have moved the fill(s) to other locations, including to the other side of the coach.  There isn't any reason that the tanks HAVE to be connected. 
>
>Another thought, a spacer on top the frame (effectively a body lift) would allow for a larger (thicker) "custom" fuel tank, maybe even large enough that you only would need one tank.  That would simplify the fill, vent and "use" plumbing. 
>
>
>--
>Mike Miller -- Hillsboro, OR -- on the Black list
>(#1)'73 26' exPainted D. -- (#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
>http://m000035.blogspot.com
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Re: [GMCnet] Fuel tank filler nipple [message #210782 is a reply to message #210767] Wed, 12 June 2013 08:48 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
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Registered: July 2007
Location: Sydney, Australia
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Senior Member
Mike,

I'm confused; I'm sitting at the dinette facing forward and can see the "box" around the filler pipe to the left of the driver seat.

Regards,
Rob M.

-----Original Message-----
From: Mike Miller

If I understand it correctly, the design and location of the fill "system" was to keep it from protruding into the living space.
--
Mike

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426
Re: [GMCnet] Fuel tank filler nipple [message #211024 is a reply to message #210782] Thu, 13 June 2013 20:44 Go to previous messageGo to next message
mike miller   United States
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
Senior Member
The "living space" in question is aft of the steps.

Robert Mueller wrote on Wed, 12 June 2013 06:48

Mike,

I'm confused; I'm sitting at the dinette facing forward and can see the "box" around the filler pipe to the left of the driver seat.

Regards,
Rob M.

-----Original Message-----
From: Mike Miller

If I understand it correctly, the design and location of the fill "system" was to keep it from protruding into the living space.
--
Mike



Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo' http://m000035.blogspot.com
Re: [GMCnet] Fuel tank filler nipple [message #211176 is a reply to message #210367] Sat, 15 June 2013 18:01 Go to previous messageGo to next message
noi is currently offline  noi   United States
Messages: 293
Registered: October 2010
Location: South of Fremont
Karma: 0
Senior Member
Greetings:

Hypothetical rear tank modification thought exercise….

If new custom fuel tanks were being made, would anything be…. gained / no significant change / detracted from…. By moving the rear tank filler nipple from the front of the rear tank to the back of the rear tank?

Re-plumbing system would be a given.

Thanks for your thoughts,

Carl P.
76 Birchaven
South of Fremont
Re: [GMCnet] Fuel tank filler nipple [message #211237 is a reply to message #211176] Sun, 16 June 2013 09:19 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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Location: S.E. Michigan
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Senior Member
noi wrote on Sat, 15 June 2013 19:01

Greetings:

Hypothetical rear tank modification thought exercise….

If new custom fuel tanks were being made, would anything be…. gained / no significant change / detracted from…. By moving the rear tank filler nipple from the front of the rear tank to the back of the rear tank?

Re-plumbing system would be a given.

Thanks for your thoughts,

Carl P.

The only thing gained would be elimination of the gravity transfer from Main to Auxiliary when the coach is significantly head down. Real and effective fuel inventory management would still be very difficult.

I have put a lot of thought into this over the years we have had the coach and I believe that the only effective thing to do is put a valve in the fill pipe to separate the two tanks. I haven't yet found a valve I like for the job.

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: [GMCnet] Fuel tank filler nipple [message #211241 is a reply to message #211237] Sun, 16 June 2013 09:31 Go to previous messageGo to next message
Jp Benson is currently offline  Jp Benson   United States
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Location: Fla
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Senior Member
Matt,

Well it would also increase fuel capacity by about a pint. 

I know it's not practical for assembled coaches but moving the fill tube above the tank level would prevent gravity transfer under most circumstances.  I would think there should be a 1/4 turn ball valve that would do the job you want but then I haven't really looked for one.



JP




>________________________________
> From: Matt Colie <matt7323tze@gmail.com>
>To: gmclist@temp.gmcnet.org
>Sent: Sunday, June 16, 2013 10:19 AM
>Subject: Re: [GMCnet] Fuel tank filler nipple
>
>
>
>
>noi wrote on Sat, 15 June 2013 19:01
>> Greetings:
>>
>> Hypothetical rear tank modification thought exercise….
>>
>> If new custom fuel tanks were being made, would anything be…. gained / no significant change / detracted from…. By moving the rear tank filler nipple from the front of the rear tank to the back of the rear tank?
>>
>> Re-plumbing system would be a given.
>>
>> Thanks for your thoughts,
>>
>> Carl P.
>
>The only thing gained would be elimination of the gravity transfer from Main to Auxiliary when the coach is significantly head down.  Real and effective fuel inventory management would still be very difficult. 
>
>I have put a lot of thought into this over the years we have had the coach and I believe that the only effective thing to do is put a valve in the fill pipe to separate the two tanks.  I haven't yet found a valve I like for the job.
>
>Matt
>--
>Matt & Mary Colie
>'73 Glacier 23 Chaumière (say show-me-air)
>Now with 4 working Rear Brakes
>SE Michigan - Twixt A2 and Detroit
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Re: [GMCnet] Fuel tank filler nipple [message #211291 is a reply to message #211241] Sun, 16 June 2013 18:13 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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Jp Benson wrote on Sun, 16 June 2013 10:31

Matt,

Well it would also increase fuel capacity by about a pint. 

I know it's not practical for assembled coaches but moving the fill tube above the tank level would prevent gravity transfer under most circumstances.  I would think there should be a 1/4 turn ball valve that would do the job you want but then I haven't really looked for one.

JP

JP,

The problem is that I want a valve that is at least a 1" port, drip tight, and remotely operated (I'm not going to crawl on the pavement to work the valve.)

I've put 53+ gallons on several times. I don't think I care about adding a pint.

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: [GMCnet] Fuel tank filler nipple [message #211305 is a reply to message #211237] Sun, 16 June 2013 19:48 Go to previous messageGo to next message
noi is currently offline  noi   United States
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Registered: October 2010
Location: South of Fremont
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Senior Member
Matt Colie wrote on Sun, 16 June 2013 07:19

The only thing gained would be elimination of the gravity transfer from Main to Auxiliary when the coach is significantly head down. Real and effective fuel inventory management would still be very difficult.


Matt - That was my initial thinking as well, but thought I would ask anyway - Thanks

Have another question - Though it probably belongs on the vapor lock thread, it is closer to this thread as it is about custom fuel tanks/changes again.

Same criteria as before, gain / no significant change / detract from.

What effect would larger diameter fuel pickup tubes and hoses have on an electric fuel pump placed as close to the fuel tanks as possible?

I don't have a diameter measurement handy of the standard fuel pickup tube, but what if it was say.... 50% larger and larger hose to match.

Not sure if I have asked the question correctly, but would such setup help reduce the flow restriction/pressure drop to aid in minimizing vapor lock?

I don't recall anyone ever asking such a question, or maybe it's just to obvious Smile

Thanks,

Carl P.
76 Birchaven
South of Fremont




Re: [GMCnet] Fuel tank filler nipple [message #211420 is a reply to message #211291] Mon, 17 June 2013 16:47 Go to previous messageGo to previous message
Tangerine is currently offline  Tangerine   United States
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Registered: February 2004
Location: Livonia, MI
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Senior Member
On 6/16/2013 7:13 PM, Matt Colie wrote:
>
> Jp Benson wrote on Sun, 16 June 2013 10:31
>> Matt,
>>
>> Well it would also increase fuel capacity by about a pint.Â
>>
>> I know it's not practical for assembled coaches but moving the fill tube above the tank level would prevent gravity transfer under most circumstances. I would think there should be a 1/4 turn ball valve that would do the job you want but then I haven't really looked for one.
>>
>> JP
> JP,
>
> The problem is that I want a valve that is at least a 1" port, drip tight, and remotely operated (I'm not going to crawl on the pavement to work the valve.)
>
> I've put 53+ gallons on several times. I don't think I care about adding a pint.
>
> Matt
Matt

If you ever find such a valve please let me know. I would like to do
the very same thing.

Gary W. Mills (Livonia MI)
. ___________
./_][__][] []| 1974 GMC M/H
.*O-------OO-* Painted Desert
"Tangerine Dream" W/New Frame
./___\.
(o\_!_/o) '74 Love Bug


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